#include <stdio.h>
#define  M  3.0e-23
#define  PI 3.1415926

#if 1
/*水的夸脱值*/
int main(int argc, char const *argv[])
{

    int num = 0; 
    printf("请输入水的夸脱数>: ");
    scanf("%d",&num);
    printf("num=%d\n",num);

    float sum = num*950/M;
    printf("%d 夸脱的水中有 %e 个水分子\n",num,sum);

    return 0;
}

#else
/*计算圆的周长，面积*/
int main(int argc, char const *argv[])
{
    float r = 0;
    float S,V;
    printf("请输入圆的半径:");
    scanf("%f",&r);
    printf("r=%f\n",r);

    V = 2*r*PI;
    S = PI*r*r;

    printf("V=%f\n",V);
    printf("S=%f\n",S);
    return 0;
}

#endif
